the objective of this study was to evaluate the effect and the interaction of phytic acid (used in fattening pig diets, mainly through of defatted corn germ meal (fgmd)), and phytase on performance, serum profile and carcass traits. thirty two pigs from a commercial line pen ar lan averaging 60.31±5.32 kg (sd) of initial body weight were used. animals were fed ad libitum during 29 days and it was measured the average daily feed intake, average daily gain and feed conversion ratio. blood samples were taken at 14th day of the experiment and a complete blood count and serum phosphorus, calcium, iron, triglycerides, cholesterol and urea concentrations were performed. levels of phosphorus and calcium in faeces also were evaluated. a greater feed intake was observed when fgmd was included in the diets (p<0.05). however, the other performance variables, carcass and hematological parameters were not influenced by both fgmd and phytase factors (p<0.05). barrows had a greater urea excretion, carcass weight and backfat thickness than females (p<0.05). in other hand, females had a greater meat yield of the chilled carcass compared to barrows (p<0.05). finally, when the phytase was added on feed, pigs had a lower level of phosphorus and calcium in faeces (p<0.05). in conclusion, diets containing higher levels of phytic acid (with fgmd as ingredient) did not affect the parameters studied.